1. Field of the Invention
This invention relates to a method for preparing fatty acid chlorides. More particularly, the invention relates to a method for preparing fatty acid chlorides comprising at least 2 aliphatically unsaturated bonds per molecule.
2. Background Information
Fatty acid chlorides are useful as reactive intermediates and are employed in a variety of organic synthetic reactions. While fatty acid chlorides can reportedly be synthesized by reacting a fatty acid with a chlorinating agent such as thionyl chloride, the reaction of a chlorinating agent with a fatty acid that contains 2 or more aliphatically unsaturated bonds per molecule produces side reactions that are thought to originate with the unsaturated bonds so that the desired fatty acid chloride is not obtained. Japanese Patent Application Laid Open (Kokai or Unexamined) Number Hei 2-9837 (9,837/1990) does teach a method for preparing acid chlorides of fatty acids that contain at least 2 aliphatically unsaturated bonds per molecule. In the method taught in this reference, the reaction is carried out by the addition of oxalyl chloride in small portions at a temperature of -15.degree. C. to 5.degree. C. to the aliphatically unsaturated fatty acid dissolved in a nonpolar solvent. While this method does inhibit the side reactions and provide the desired fatty acid chloride, it uses nonpolar solvent and requires that the reaction temperature be maintained in an extremely narrow and low temperature range. The reference method is therefore unsuitable for large-scale reactions and has poor productivity.
The inventors achieved the present invention as a result of extensive research directed to solving the problems described above. The objective of the present invention is to provide a method for preparing fatty acid chlorides comprising at least 2 aliphatically unsaturated bonds per molecule.